Joshua Caldwell
Physical Scientist
U.S. Naval Research Laboratory

Towards Low-Loss, Infrared and THz Nanophotonics and Metamaterials: Surface Phonon Polariton Modes in Polar Dielectric Crystals

Location: EB1 Room 1011

Friday, November 21st 2014 - 11:00 am

The field of nanophotonics is based on the ability to confine light to sub-diffractional dimensions. Up until recently, research in this field has been primarily focused on the use of plasmonic metals. However, the high optical losses inherent in such metal-based surface plasmon materials has led to an ever-expanding effort to identify, low-loss alternative materials capable of supporting sub-diffractional confinement. One highly promising alternative are polar dielectric crystals whereby sub-diffraction confinement of light can be achieved through the stimulation of surface phonon polaritons within an all-dielectric, and thus low loss material system. Both SiC and hexagonal BN are two exemplary SPhP systems, which along with a whole host of alternative materials promise to transform nanophotonics and metamaterials in the mid-IR to THz spectral range. In addition to the lower losses, these materials offer novel opportunities not available with traditional plasmonics, for instance hyperbolic optical behavior in natural materials such as hBN, enabling super-resolution imaging without the need for complex fabrication. This talk will provide an overview of the SPhP phenomenon, a discussion of what makes a 'good' SPhP material and recent results from SiC and the naturally hyperbolic material, hBN from our research group.

Dr. Joshua Caldwell was awarded his bachelors of Chemistry from Virginia Tech in 2000 before heading to the University of Florida where he received his PhD in Physical Chemistry in 2004. There he used magnetic resonance methods to investigate electron-nuclear spin coupling within low-dimensional quantum wells and heterostructures. He accepted a postdoctoral fellowship at the Naval Research Laboratory, using optical spectroscopy as a means of understanding defects within wide-band gap semiconductors. He was transitioned to permanent staff in 2007, where he began work in the field of nanophotonics, investigating coupling phenomena within plasmonic materials. More recently, Dr. Caldwell merged his prior work in wide band gap semiconductor materials with his efforts in nanophotonics, leading to his efforts to use undoped, polar dielectric crystals for low-loss, sub-diffraction optics. Dr. Caldwell recently finished a sabbatical at the University of Manchester with Prof. Konstantin Novoselov, investigating the use of van der Waals crystals such as hexagonal boron nitride for mid-IR to THz nanophotonics.

North Carolina State University